This invention generally relates to electrochemical systems for storage and release of electrical energy. In particular, the present invention relates to electrochemical systems for use in electronic circuits, for example, as capacitors or batteries. More particularly, the present invention relates to electrochemical systems for operation in electronic circuitry, for example, as capacitors or batteries, with either a non-liquid, organic solution, aqueous solution or a protonic medium electrolyte material positioned between the electrodes.
Further still, the present invention relates to improved designs for bi-polar assemblies that address the deficiencies in existing bi-polar designs. In particular, this invention relates to an assembly of a plurality of single cells of an electrochemical system.
As electronic devices and other electrical apparatuses become increasingly more portable and provide more functionality, advances must be made in the devices of such devices that enable such portability. As is often the case with current electronics technology, the limiting factor in both size and functionality of an electronic apparatus is the size and weight of its component parts. In particular, the size and weight of its energy storage components. Additionally, the miniaturization of electronics has seen the push towards integrating various components into a single device to save both room and weight within both portable and stationary devices.
The current main energy source used for portable electronics is the electrochemical battery and/or the electrochemical capacitor. One of the limiting features of such current energy storage devices is the packaging of the electrochemical system. Prior art enclosures for flat and low height designs have suffered from several disadvantages. Coin cells for round shaped assemblies have needed to be crimped or swagged closed which requires expensive precision tooling. Further, such a method of enclosure requires accurate placement and/or control of closing pressures which can be very time consuming. Prismatic cell designs for rectangular and square shaped assemblies require precise corner radii and equivalent closing force across the entire area of the design to ensure good contact between the casing and the internal cells. While useful for their purpose, these prior art designs have forced higher production costs and longer production times due to the precision and technically complex assembly methods.
Further, in both coin and prismatic designs a grommet is needed to prevent shorting between the two poles of the electrochemical system. Should the electrochemical device consist of a plurality of cells in a stack then the grommet must serve to insulate the edge of the pack from the enclosure and insulate the two portions of the enclosure that contact the two poles of the device. Thus the grommet acts to prevent the manufacture of some desirable forms of connections to a plurality of cells.
It is, therefore, desirable to provide a multi-cell energy storage device which may comprise either an electrochemical capacitor, a double-layer capacitor or a battery. In an electrochemical capacitor version of the present invention, which may also be referred to as a pseudo-capacitor or batcap, the electrodes comprise material that may participate in reversible charge transfer reactions. Thus, a portion of the energy is stored in the double-layer at the surface of the electrodes and another portion is contributed by the charge transfer reactions. In a double-layer capacitor version of the present invention, essentially all of the energy is stored in the double layer at the surface of the electrodes. In a battery version of the present invention, the anode and cathode materials are specifically chosen so that each reacts during operation of the cell. The chemical energy that is stored in the electrodes is converted to electrical energy via charge transfer reactions of active materials. It is also desirable to provide a new packaging for an electrochemical single or multi-cell energy storage device wherein the cells in a multi-cell design may be in series, parallel or a combination thereof by virtue of the device's construction in one integrated structure.